Viagra is the first pill that proved to be effective in improving an erection in most men with erectile dysfunction. Since Viagra introduction in 1998 no other treatment has gained such popularity. Today the are plenty of online offers, which make it possible to order Viagra without seeing a doctor face to face. Viagra helps men who have difficulties with maintaining or achieving erections because of some medical problems. However, it will not cause greater sexual desire. For Viagra to function sexual stimulation is required. Viagra effect is revealed in blocking enzymes that stop chemicals released in the course of a sexual stimulation for producing an erection. With Viagra these chemicals survive longer and that is why sexual stimulation is required for Viagra to have effect. By and large, almost 70 % of men with erectile dysfunction use Viagra successfully. It is advised to take one pill per day 30 to 60 minutes before coitus. A dose increased beyond the amounts recommended will not increase the effect, but will increase possible side-effects.